ever stolen anything?” In probable-lie comparison question tests, the instructions are designed to induce innocent people to answer in the negative, even though most are lying. Innocent examinees are expected to experience concern about these answers that shows in their physiological responses. In directed-lie tests, examinees are instructed to respond negatively and untruthfully to comparison questions (e.g., “During the first 20 years of your life, did you ever tell even one lie?”). In both forms of test, the expectation is that innocent examinees will react more strongly to the comparison questions, and guilty examinees will react more strongly to relevant questions.
Comparison question tests are widely applicable and are used both in specific-incident investigation and in screening. Some of the varieties of comparison question tests are described very briefly below. They vary in question selection, test construction, test scoring and interpretation, and other characteristics not discussed here (see Raskin and Honts, 2002, for more detail).
The Reid comparison question test, also known as the modified general question test, was the earliest form of comparison question test. It includes probable-lie comparison questions and is interpreted by the examiner’s global evaluation of the charts, combined with other observations made during the examination. Other characteristics of the test include a discussion of the examinee’s moral values during the test procedure and the use of a “stimulation” test between the first and second presentations of the questions (see Reid and Inbau  or Raskin and Honts  for more detail).
The zone comparison test, which was developed by Backster (1963), is named for the three “zones” or blocks of time during the test: the relevant questions (called the red zone), the probable-lie comparison questions (the green zone), and other questions (the black zone). Black zone questions are included to uncover examinee concerns about an issue outside of the scope of the red and green zones, such as involvement in another crime. Each zone is presumed to be threatening to someone; however, depending on the examinee’s mental set, it is anticipated that one particular zone is more threatening than are the other two (information from Donald Krapohl, U.S. Department of Defense Polygraph Institute, private communication, October 5, 2001). This was the first comparison question test to incorporate a numerical scoring system. It used a seven-point